Final answer:
In the given sentence, 'The Comets were winning the game when the power went out.', the complete verb phrase is 'were winning' with 'were' as the helping verb and 'winning' as the main verb, which describes an ongoing action in the past.
Step-by-step explanation:
The sentence "The Comets were winning the game when the power went out." contains a helping verb (also known as an auxiliary verb) which is "were", and the main verb of the sentence is "winning".
Together, they form the complete verb phrase "were winning". This verb phrase indicates an action that was taking place at a certain point in time, specifically when the interruption of the power outage occurred.
In the realm of English grammar, verbs can be accompanied by auxiliaries to convey different tenses, aspects, moods, or voices. For example, in the sentence provided, "were winning" is in the past continuous tense, which is used to describe an action that was ongoing in the past.